Vehicle lamp assembly

ABSTRACT

A vehicle lamp assembly for a vehicle includes a light source unit (e.g., one or more LEDs) mounted to the vehicle for providing illumination and a heat sink thermally coupled to the light source unit for dissipating generated heat therefrom. An air guide is secured to the vehicle for guiding air to the heat sink to remove heat therefrom.

This application is related to the U.S. patent application entitled“VEHICLE LAMP ASSEMBLY” application Ser. No. 12/023,895, filedconcurrently herewith, commonly assigned to Honda Motor Co., Ltd. andexpressly incorporated herein by reference.

BACKGROUND

The present disclosure generally relates to vehicle lamp assemblies, andmore particularly relates to an improved vehicle lamp assembly having aheat sink thermally coupled to a light source, such as a light emittingdiode (LED), for dissipating generated heat therefrom. In at least oneembodiment, the heat sink receives an airflow from an air guide havingan inlet formed in a forward bumper portion of a vehicle in which theimproved vehicle lamp assembly is provided.

Vehicle lamp assemblies employing one or more LEDs as the light sourcefor providing illumination are known to generate heat typically inexcess of heat generated from more conventional light sources (e.g.,incandescent bulbs). Heat removal is a particular concern in LED lampassemblies because accumulated heat can degrade the performance of LEDs.In particular, light output from a LED typically decreases as thetemperature of the LED increases so care must be taken to avoid allowingheat to accumulate around an LED and raise the temperature to a levelthat causes the light output or illumination from the LED to drop belowan acceptable amount. In addition to performance degradation, excessheat around a LED can even lead to ultimate failure of the LED.

Vehicle lamp assemblies, including LED lamp assemblies, sometimesinclude heat sinks for purposes of removing heat generated by the lightsource. For example, a heat sink can be thermally coupled to the lightsource (e.g., one or more LEDs) for dissipating generated heattherefrom. Such heat sinks often include a plurality of fins forincreasing the amount of heat that can be dissipated by the heat sink.

SUMMARY

According to one aspect, a lamp assembly for a vehicle is provided. Moreparticularly, in accordance with this aspect, the lamp assembly includesa light source unit mounted to the vehicle for providing illumination. Aheat sink is thermally coupled to the light source unit for dissipatinggenerated heat therefrom. An air guide is secured to the vehicle forguiding air to the heat sink to remove heat therefrom.

According to another aspect, a vehicle lamp cooling assembly for avehicle is provided. More particularly, in accordance with this aspect,the vehicle lamp cooling assembly includes a heat sink thermally coupledto a light source unit for dissipating heat generated therefrom. An airduct has an inlet at a first end for receiving an airflow when thevehicle is moving. The air duct further has a second end positionedadjacent the heat sink for passing the airflow to the heat sink tofacilitate heat dissipation by the heat sink. Still further, the airduct has a passageway extending between the first end and the second endfor directing airflow received in the inlet to the second end.

According to still another aspect, an air guide for cooling a vehiclelamp assembly is provided. More particularly, in accordance with thisaspect, the air guide includes an inlet formed in a forward bumperportion of a vehicle for receiving an airflow when the vehicle is movingforward. A sinuous passageway extends from the inlet into the forwardbumper portion. An outlet end is formed adjacent a vehicle lamp assemblyheat sink for removing heat from the vehicle lamp assembly. The airflowis received into the inlet, directed by the passageway, and provided tothe heat sink for cooling thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic elevational view, partially in cross-section, of avehicle lamp assembly having a heat sink with an angled surface sectionfor urging environmental elements to run off the heat sink.

FIG. 2 is an enlarged cross-sectional view of the heat sink showingenvironmental elements being urged off the heat sink.

FIG. 3 is an enlarged side elevational view of the heat sink of FIG. 1.

FIG. 4 is an enlarged cross-sectional view of an alternative heat sinkand heat sink mounting arrangement for urging environmental elements torun off the heat sink.

FIG. 5 is a cross-sectional view of a conventionally mounted heat sinkwhereon environmental elements tend to collect and accumulate renderingthe heat sink less effective at dissipating heat.

FIG. 6 is a schematic plan view of a lamp assembly for a vehicle,partially in cross-section, having an air guide for guiding airflow to aheat sink thermally coupled to a light source unit of the lamp assemblyfor removing heat therefrom.

FIG. 7A is a partial rear elevational view of the lamp assembly of FIG.6.

FIG. 7B is a partial rear elevational view like FIG. 7A, but of analternative lamp assembly having an air guide with a first endpositioned higher than a second at the heat sink.

FIG. 8A is a partial cross-sectional view of the lamp assembly of FIG. 6taken along the line 8-8.

FIG. 8B is a partial cross-sectional view like FIG. 8A, but of thealternative lamp assembly of FIG. 7B.

FIG. 9 is a schematic elevational view, partially in cross-section, of alamp assembly having a heat sink thermally coupled to a light sourceunit and housed in a protective cover disposed about the heat sink.

FIG. 10 is a partial cross-sectional plan view of the lamp assembly ofFIG. 9.

DETAILED DESCRIPTION

Referring now to the drawings, wherein the showings are only forpurposes of illustrating one or more exemplary embodiments, FIG. 1 showsa lamp assembly 10 for a vehicle including a light source unit 12. Thevehicle lamp assembly 10 and the light source unit 12 can be operativelymounted to an associated vehicle 14 for providing illumination therefor.The lamp assembly 10 could be, for example, a vehicle head lamp, foglight, or the like. The illustrated lamp assembly 10 includes a heatsink 16 thermally coupled to the light source unit 12 for dissipatinggenerated heat therefrom. As shown, the light source unit 12 can bemounted to and/or in a lamp housing 18, which is itself mounted to theassociated vehicle 14. The lamp housing 18 can include a main housingportion 18 a having reflectors (not shown) for focusing or directinglight provided by the light source unit 12 and a lens portion 18 b at aforward end for allowing light to pass out of the lamp housing 18.

The light source unit 12 can be a LED package or packages employing oneor more LEDs for providing illumination for the vehicle 14. Asschematically illustrated, the light source unit 12 can be a LED lightsource unit including one or more lens portions 20 mounted to a base orsupport block 22. Alternatively, the light source unit 12 can be a LEDlight source without a lens portion or the light source unit 12 couldcomprise one or more conventional light bulbs (i.e., incandescent bulbs)or other light emitting devices. The support block 22 can contain theremainder of a LED package or packages and/or can house controlcircuitry for controlling the light source unit 12 and/or electricalconnections for powering the light source unit 12. In the illustratedembodiment, the one or more lens portions 20 are mounted so as to bepositioned within the lamp housing 18 and the support block 22 ismounted to a rear side of the lamp housing 18 forming together with thelamp housing 18 a lamp housing exterior. Thus, the depicted LED lightsource unit 12 is operatively mounted to the lamp housing 18 with thelens portions 20 mounted within the lamp housing 18 and the supportblock 22 mounted to the lamp housing exterior.

As shown, the heat sink 16 is thermally coupled to the light source unit12 of the lamp assembly 10, which can be referred to as a LED vehiclelamp assembly when employing one or more LEDs as the light source unit12. In particular, the heat sink 16 can be mounted to the support block22 for dissipating heat generated by the light source unit 12. Becausethe support block 22 is mounted to the rear side of the lamp housing 18and forms the exterior of the lamp assembly 10, the heat sink 16 can beconsidered as being mounted to the exterior of the lamp assembly 10,whereas the light source unit 12 is at least partially housed within thelamp housing 18, particularly the one or more lens portions 20 of thelight source unit 12.

With additional reference to FIG. 2, the heat sink 16 has a main bodyportion 28, spaced apart fins 30 extending from the main body portion 28and an angled surface section 32 on the main body portion 28 disposedbetween adjacent ones of the spaced apart fins 30 for urgingenvironmental elements to run off the heat sink 16. In the illustratedembodiment, the fins, which can be referred to as heat dissipating fins,are upstanding relative to or from the main body portion 28. The angledsurface section 32, with additional reference to FIG. 3, can beconsidered a single surface defined in the single plane or a pluralityof angled surface sections (such as surface sections 32 a,32 b,32 c,32d,32 e,32 f), one each disposed between adjacent pair of the fins 30 forpromoting run off of environmental elements received thereon, such asillustrated environmental elements 34. Of course, as will be understoodand appreciated by those skilled in the art, the depicted number of fins30 or angled surface sections 32 a-f need not be as illustrated and canbe provided in other shapes and/or configurations other than thoseillustrated.

The main body portion 28 can alternately be referred to as including abottom or lower surface 36 from which the fins 30 extend, wherein theangled surface section 32 (or sections 32 a-f) is (are) then a portionof the lower surface 36 disposed between adjacent ones of the spacedapart fins 30. Opposite the lower surface 36 and the angled surfacesection 32 is an opposite or mounting surface 38 that is mounted to thesupport block 22. As best shown in FIG. 2, the lower surface 36 and theangled surface section 32 which the lower surface includes are formed ina plane oriented at an acute angle relative to a plane in which theopposite surface 38 is formed for purposes of urging the environmentalelements 34 to run off heat sink 16 as indicated by arrows 42.

In the embodiment illustrated in FIGS. 1-3, the opposite surface 38 isorthogonally oriented relative to a normal direction of gravity, such asindicated by arrow 40. That is, the opposite surface 38 is normallydisposed in a horizontal plane. The normal direction of gravityrepresented by the arrow 40 is such when the vehicle 14 to which thedepicted lamp assembly 10 is mounted is traveling on a surface that isoriented approximately perpendicular relative to gravity. When thevehicle travels on an incline or hill, the normal direction of gravitywill be at some other direction than represented by arrow 40. The fins30 of heat sink 16 depicted in FIGS. 1-3 extend at an acute angle fromand relative to the angled surface section 32 and the lower surface 36.

In operation, the heat sink 16 and its angled surface sections 32 a-fcan be provided on the vehicle 14 such that they are exposed to road andenvironmental conditions when the vehicle is driven. If allowed tocollect on the heat sink 16, environmental elements could degrade theperformance of the heat sink and lessen its ability to dissipate heatfrom the light source unit 12. By being angled acutely relative to thenormal direction of gravity 40 (i.e., surface sections 32 a-f are notorthogonal relative to the arrow 40 under generally flat drivingconditions), the angled surface 32 (or sections 32 a-f) promote runoffof the environmental elements 34 as best shown in FIG. 2. That is, thesloped surface 32 directs environmental elements to run off the heatsink 16 and not collect thereon.

With reference to FIG. 4, a heat sink 16′ is illustrated according to analternate embodiment. The heat sink 16′ can be thermally coupled to alight source unit (only support block 22′ of light source unit shown inFIG. 4) for dissipating generated heat therefrom. Like the heat sink ofFIGS. 1-3, the heat sink 16′ has a main body portion 28′, spaced apartfins (only one fin 30′ shown) extending from the main body portion 28′,and an angled surface section 32′ disposed between adjacent ones of thespaced apart fins for urging environmental elements 34′ to run off theheat sink 16′. The main body portion 28′ includes a lower surface 36′from which the fins 30′ extend, wherein the angled surface section 32′is a portion of the lower surface 36′. The main body portion 28′ furtherincludes an opposite surface 38′ formed on a side of the main bodyportion 28′ opposite the lower surface or angled surface section 32′.

Unlike the heat sink 16 of FIGS. 1-3, the heat sink 16′ is particularlyoriented or mounted to the support block 22′ for urging theenvironmental elements 34′ to run thereof as indicated by arrows 42′.More particularly, the lower surface 36′ and/or angled surface section32′ are formed in a plane generally parallel to a plane in which theopposite surface 38′ is formed. As shown, the main body portion 28′ isoriented such that the angled surface section 32′ is angularly disposedrelative to a normal direction of gravity 40′. Unlike the fins 30 of theheat sink 16, the fins 30′ extend orthogonally from the lower surface36′, which includes the angled surface section 32′. In other words, theheat sink 16′ is positioned on its lamp housing such that the angledsurface sections thereof are angularly disposed relative to thehorizontal plane (a horizontal plane that is oriented approximatelynormal relative to the normal direction of gravity 40′). In contrast, inthe arrangement depicted in FIGS. 1-3, the opposite surface 38 isdisposed in a horizontal plane.

With reference to FIG. 5, a prior art mounting arrangement is shown witha heat sink 46 mounted flatly on a support block 48, which could be athe support block of a light source unit such as a LED. As shown, theheat sink 46 can have, for example, a main body portion 50, spaced apartfins extending from the main body portion 50 (only one fin 52 shown),and a lower surface 54 from which the fins extend (and with surfacesections defined between adjacent fins). When exposed to theenvironment, the illustrated heat sink 46, and particularly the lowersurface 54 or portions thereof between adjacent fins, can undesirablycollect environmental elements 56 thereon because, unlike the heat sinks16 and 16′, the lower surface is not oriented at an angle and thus thereis no gravitational urging on environmental elements on the surface 54to move these off the heat sink. This can adversely affect theperformance of the heat sink 46 and its ability to dissipate heatgenerated by the light source unit to which it is thermally coupled.

With reference now to FIGS. 6, 7A and 8, a lamp assembly 60 for avehicle 62 is shown. The lamp assembly 60 includes a light source unit64, which can be a LED light source unit, that is operatively mounted tothe vehicle 62 for providing illumination therefor. In particular, thelight assembly 60 could be, for example, a vehicle head lamp, fog light,or the like, and the light source unit 64 could be a LED package orpackages employing one or more LEDs for providing illumination for thevehicle 62. As schematically shown, the light source unit 64 can be aLED light source unit including one or more lens portions 66 mounted toa base or support block 68. The support block 68 can contain theremainder of a LED package or packages and/or can house controlcircuitry for the light source unit 64 and/or electrical connections forpowering the light source unit 64. As will be understood and appreciatedby those skilled in the art, the light source unit 64 couldalternatively comprise one or more conventional light bulbs or otherlight emitting devices.

The illustrated lamp assembly 60 includes a heat sink 70 thermallycoupled to the light source unit 64 for dissipating heat therefrom. Asshown, the light source unit 64 can be mounted to and/or in a lamphousing 72, the lamp housing being mounted to the vehicle 62. Like thelamp housing 18, the lamp housing 72 can include a main housing portion72 a having reflectors (not shown) for focusing or directing lightprovided by the light source unit 64 and a lens portion 72 b at aforward end for allowing light to pass out of the lamp housing. Asshown, and like the embodiments of FIGS. 1-4, the one or more lensportions 66 can be mounted so as to be positioned within the lamphousing 72 and the support block 68 can be mounted to a rear side of thelamp housing 72 forming together with the lamp housing 72 a lamp housingexterior.

As shown, the heat sink 70 is thermally coupled to the light source unit64 of the lamp assembly 60. In particular, the heat sink 70 can bemounted to the support block 68 for dissipating heat generated by thelight source unit 64. Since the support block 68 is mounted to the lamphousing exterior, the heat sink 64 is mounted outside of the lamphousing 72 but thermally coupled to light source unit 64, at least aportion of which (i.e., lens portion 66) is mounted or housed within thelamp housing 72. In one embodiment, the heat sink 70 can be constructedthe same or similar to one of the heat sinks 16 or 16′ discussedhereinabove (e.g., having an angled surface section or sections).

As shown, the heat sink 70 can include a main body portion 74, spacedapart fins 76 extending from the main body portion 74 and a surfacesection 78 (or sections 78 a-f) on the main body portion 74 disposedbetween adjacent ones of the spaced apart fins 76. Although not showingthe surface sections 78 a-f can be constructed so as to be angledrelative to a horizontal plane when the heat sink is mounted flatly(like heat sink 16) or can be angularly oriented by mounting the heatsink at an appropriate angle (like heat sink 16′). Alternatively, aswill be appreciated by those skilled in the art upon reading the subjectdisclosure, the heat sink 70 could be of some other constructionsuitable for dissipating heat from the light source unit 64.

As shown, an air guide 82 is secured to the vehicle 62 for guiding airto the heat sink 70 to remove heat therefrom more rapidly than wouldotherwise be achieved without the air guide. The arrangement of thelight source 64, heat sink 70 and air guide 82, collectively referred toherein as a vehicle lamp cooling assembly, provides for rapid heatremoval from the heat sink 70, particularly during driving of thevehicle 62. The air guide 82, alternately referred to herein as an airduct, is specifically formed in a bumper portion 62 a of the vehicle 62.The air guide 82 of the illustrated embodiment of FIGS. 6, 7A and 8Aincludes or has an air guide inlet 84 formed at a first end 86 of theair guide 82 for receiving an airflow from atmosphere represented byarrow 88, particularly when the vehicle 62 is moving. A second end 90 ofthe air guide 82 is positioned adjacent the heat sink 70 so as to guideor pass the airflow to the heat sink to facilitate heat dissipation bythe heat sink.

In particular, the air guide 82 defines or has a passageway 92 extendingbetween the first end 86 and the second end 90 for directing the airflow88 received in the inlet 84 to the second end 90, as indicated by arrows94. The air guide 82 is positioned to guide the airflow therealong anddischarge the same onto the heat sink 70 as indicated by arrows 96.Particularly, the air guide 82 is positioned to guide air, includingairflow 88, to the fins 76 of the heat sink 70. More particularly, theair guide 82 and the spaced apart fins 76 are oriented relative to oneanother such that the air guide 82 directs air between the fins 76 whenthe vehicle 62 is moving. Alternatively, though not shown, the air guide82 can be oriented to direct airflow guided therethrough when thevehicle is moving to a location immediately above the heat sink 70.

As best illustrated in FIG. 6, the air guide 82 defines the passageway92 as a circuitous path, also referred to herein as a serpentine-shapedor sinuous path or passage, from the first end 86 that is open to anopen air source (i.e., atmosphere) to the second end 90 located at theheat sink 70. The circuitous path or passageway 92 for the airflowprevents or reduces (i.e., inhibits) the possibility of environmentalelements from passing through the air guide 82 to the heat sink 70.Moreover, the air guide 82 can have an elevated or raised portion 82 aforming an apex disposed between the first and second ends 86,90 alongthe circuitous passage 92. The raised portion 82 a can redirectparticles or environmental elements that enter the inlet 84, but areunable to pass through the circuitous passage 92, back out the inlet 84to atmosphere. Additionally, air flow passing the apex or raised portion82 a is subsequently directed downwardly onto the heat sink 70.

In the construction depicted, the light source 64 and heat sink 70 arepositioned internally relative to the bumper portion 62 a, or at least aforward edge thereof, of the vehicle 62. In this configuration, the airguide 82 is formed through the bumper portion 62 a with the inlet 84forming an aperture in the bumper portion 62 a that is open toatmosphere. Passageway 82 extends into the bumper portion 62 a to theheat sink 70.

With reference to FIGS. 7B and 8B, an air guide 82′ is shown accordingto an alternate embodiment. In most respects, except as notedhereinbelow, the air guide 82′ is the same or similar to the air guide82 of FIGS. 6, 7A and 8A. In particular, the air guide 82′ has an inlet84′ at a first end 86′ for receiving an airflow when the vehicle towhich the air guide 82′ is attached is moving. A second end 90′ of theair guide 82′ is positioned adjacent and over heat sink 70 for passingairflow to the heat sink to facilitate heat dissipation thereby. Theheat sink 70 is thermally coupled to a light source 64 unit for removingheat from the light source unit as already described herein.

Unlike the air guide 82, the air guide 82′ is constructed such that itsfirst end 86′ is located at a higher position relative to a height ofthe vehicle to which the air guide 82′ is attached than the second end90′ which is at the heat sink 70. In particular, the first end 86′ islocated sufficiently higher than the second end 90′ relative to a heightof the vehicle to create a “chimney effect” for dissipating heat fromthe heat sink 70 through the air guide 82′ from the second end 90′ tothe first end 86′ when the vehicle is in a static condition (i.e., notmoving). Thus, heat generated by the heat sink 70 will rise through theair guide 82′ when no airflow is flowing toward the heat sink 70 (e.g.,when the vehicle is stopped). As shown, the second end 90′ of the airguide 82′ can be over or disposed about the heat sink 70 to encompass orenclose the same for facilitating the chimney effect.

With reference to FIGS. 9 and 10, a lamp assembly 100 for a vehicle isillustrated. The lamp assembly 100 includes a light source unit 102,which can be a LED light source unit, that is operatively mounted to avehicle for providing illumination therefor. The light assembly 100 canbe, for example, a vehicle head lamp, fog light, or the like, and thelight source unit 102 could be a LED package or packages employing oneor more LEDs for providing illumination for the vehicle on which thelamp assembly 100 is mounted. As schematically shown, the light sourceunit 102 can be a LED light source unit including one or more lensportions 104 mounted to a base or support block 106. The support block106 can contain the remainder of a LED package or packages and/or canhouse control circuitry for the light source unit 102 and/or electricalconnections for powering the same. As will be understood and appreciatedby those skilled in the art, the light source unit 102 couldalternatively comprise one or more conventional light bulbs or otherlight emitting devices.

The illustrated lamp assembly 100 includes a heat sink 108 thermallycoupled to the light source unit 102 for dissipating heat therefrom. Asshown, the light source unit 102 can be mounted to and/or in a lamphousing 110, which can include a main housing portion 110 a and a lensportion 110 b. The lens portion or portions 104 can be mounted so as tobe positioned within the lamp housing 110 and the support block 106 canbe mounted to a rear side of the lamp housing 110 forming togethertherewith a lamp housing exterior.

As shown, the heat sink 108 is thermally coupled to the light sourceunit 102 of the lamp assembly 100. In particular, the heat sink 108 canbe mounted to the support block 106 for dissipating heat generated bythe light source unit 102. Since the support block 106 is mounted to thelamp housing exterior, the heat sink 108 is mounted outside of the lamphousing 110 but is thermally coupled to the light source unit 102, atleast a portion of which (i.e., lens portion 104) is mounted or housedwithin the lamp housing 110. In one exemplary construction, the heatsink 108 can include a main body portion 112 and spaced apart fins 114extending from the main body portion 112 as illustrated. Alternatively,as will be appreciated by those skilled in the art, the heat sink 108could be of some other construction suitable for dissipating heat fromthe light source unit 102.

With the heat sink 108 mounted to the lamp housing exterior, the heatsink 108 and its fins 114 are potentially in position to be exposed toenvironmental elements (e.g., mud, water, dirt, etc.). To prevent suchenvironmental elements from reaching the heat sink 108 and adverselyaffecting the performance of the heat sink, a protective cover 116 isprovided to house or enclose the heat sink 108. The protective cover 116protects the otherwise exposed heat sink 108 and its fins 114 fromexposure to environmental elements.

To prevent heat buildup from occurring within the protective cover 116,one or more apertures or holes are defined or positioned at optimumlocations on the cover 116 for allowing airflow through the cover whilepreventing or reducing the likelihood of environmental elements fromreaching and decreasing the performance of the heat sink 108. In theillustrated embodiment, one or more inlet apertures 118 are defined inthe cover 116 and one or more outlet apertures 120 are also defined inthe cover 116. In general, the one or more outlet apertures 120 areoriented at positions above or higher than the positions of the one ormore inlet apertures 118. As a result, hot air around the heat sink 108,which is somewhat contained by the cover 116, creates an increase in airpressure. Air surrounding the cover 116 is generally cooler than theheated air within the cover 116 surrounding the heat sink 108. Thepositioning of the apertures 118,120 allows hot air from within thecover 116 to flow out into the cooler air, and more specifically suchhot air is urged out into the cooler air, due to the pressuredifferential between the hot air within the cover 116 and thesurrounding ambient air. This airflow caused by the pressuredifferential will facilitate cooling of the heat sink fins 114 whileprotecting the same from exposure to environmental elements.

The exemplary embodiment has been described with reference to thepreferred embodiments. Obviously, modifications and alterations willoccur to others upon reading and understanding the preceding detaileddescription. It is intended that the exemplary embodiment be construedas including all such modifications and alterations insofar as they comewithin the scope of the appended claims or the equivalents thereof.

1. A lamp assembly for a vehicle, comprising: a light source unitmounted to the vehicle for providing illumination; a heat sink thermallycoupled and disposed adjacent to said light source unit for dissipatinggenerated heat therefrom; and an air guide secured to the vehicle toguide air to the heat sink to remove heat therefrom, wherein said airguide is formed in a bumper portion of the vehicle, said air guideincludes an air guide inlet formed at a first end spaced apart from saidheat sink for receiving an airflow from the atmosphere when the vehicleis moving, a second end of said air guide is positioned adjacent saidheat sink so as to guide airflow to said heat sink, and wherein saidfirst end is located at a higher position relative to a height of thevehicle than said second end at said heat sink.
 2. The lamp assembly ofclaim 1 wherein said first end is located sufficiently higher than saidsecond end relative to said height of the vehicle to create a chimneyeffect for dissipating heat from the heat sink through the air guidefrom said second end to said first end when the vehicle is in a staticcondition.
 3. The lamp assembly of claim 1 wherein said second end ispositioned to direct said airflow immediately above said heat sink whenthe vehicle is moving to facilitate heat dissipation by the heat sink.4. The lamp assembly of claim 1 wherein said heat sink includes a mainbody portion and spaced apart fins extending from said main bodyportion, said air guide positioned to guide air to said fins of saidheat sink.
 5. The lamp assembly of claim 4 wherein said air guide andsaid spaced apart fins are oriented such that said air guide directs airbetween said fins when the vehicle is moving.
 6. The lamp assembly ofclaim 4 wherein said air guide is oriented to direct airflow, which isguided through said air guide when the vehicle is moving, immediatelyabove said heat sink fins.
 7. The lamp assembly of claim 4 wherein saidheat sink is externally mounted relative to a lamp housing in which saidlight source unit is received, said heat sink including angled surfacesections disposed between each adjacent pair of said heat dissipatingfins that are angled relative to a horizontal plane for promoting runoff of environmental elements received thereon.
 8. The lamp assembly ofclaim 1 wherein said light source unit includes at least one lightemitting diode (LED).
 9. The lamp assembly of claim 1 wherein said airguide defines a circuitous path from a first end that is open to an openair source to a second end located at said heat sink.
 10. A vehicle lampcooling assembly for a vehicle, comprising: a heat sink thermallycoupled to a light source unit for dissipating heat generated therefrom;and an air duct having an inlet at a first end for receiving an airflowwhen the vehicle is moving, a second end positioned adjacent said heatsink for passing said airflow to said heat sink to facilitate heatdissipation by said heat sink, and a passageway extending between saidfirst end and said second end for directing airflow received in saidinlet to said second end, wherein said light source and said heat sinkare positioned internally relative to a bumper portion of the vehicle,said air duct formed through said bumper portion with said inlet formingan aperture in said bumper portion open to atmosphere and spaced apartfrom said heat sink, said passageway extending into said bumper portionto said heat sink, and said second end of said air duct disposedadjacent said heat sink for facilitating heat dissipation thereby, andwherein said first end is located at a higher position relative to aheight of the vehicle than said second end at said heat sink.
 11. Thevehicle lamp cooling assembly of claim 10 wherein said inlet at saidfirst end is oriented relative to said second end such that heatdissipated by said heat sink generally rises from said second end tosaid first end through said passageway when the vehicle is in a staticcondition.
 12. The vehicle lamp cooling assembly of claim 11 whereinsaid airflow received into said inlet when the vehicle is moving isdirected by said air duct downwardly onto said heat sink.
 13. Thevehicle lamp cooling assembly of claim 10 wherein said heat sinkincludes fins through which said air duct directs said airflow when thevehicle is moving.
 14. The vehicle lamp cooling assembly of claim 10wherein said heat sink includes fins over which said air duct directssaid airflow when the vehicle is moving.
 15. The vehicle lamp coolingassembly of claim 10 wherein said passageway is formed as aserpentine-shaped passageway that inhibits environmental elements fromreaching said heat sink.
 16. The lamp assembly of claim 1 wherein saidheat sink includes spaced apart fins and said second end of said airguide is positioned to direct air exiting said second end into saidfins.
 17. The lamp assembly of claim 1 wherein said inlet substantiallyfaces forward relative to a direction of travel of the vehicle.